Around April 2015, I used FL to comment - at the time I was only liking and commenting. I did so for around 2 weeks on a brand new account, with around 150 comments and 300 likes a day. I wasn't banned, but I ceased the process pretty quickly.
Because you can only really control the contents of a comment when setting it up, along with which tag/location/user the comment will be posted on, it's hard to put together a comment that isn't ambiguous, spammy or just downright doesn't make sense. I found a lot of time I was getting replies in comment threads which I had simply commented things like "Great post" etcetera on. Looked really spammy and immediately seemed needy as a brand.
I think if you're going to do it, just start out slow - as with all FL settings and then scale up. Ensure you pick a tag or niche to comment on that you can be 90% sure will be applicable to the comment you're posting. Lots of people piggyback hashtags, so it's worth researching which tags are least diluted and contain relatively the same imagery in each. For instance, if you pick #fashionblogger there will likely be brands which attach these tags but have no "fashion blogger" type imagery in the post, so commenting "Amazing shoes!" will not always bode well for you.
It's tricky to master the perfect, non-spammy / non-ambiguous comment and to still not look like a complete idiot, but I'd say worthwhile if you can give the impression you have genuine interest in the posters image.